Conventional burn-off ovens of the batch type are used to incinerate contaminant or undesired coatings. Typically these burn-off ovens treat hangers or part support structures for carrying parts to be coated via a wet or dry coating system which system has conveyance means such as a monorail, chain on edge, belt driven or other transfer mechanism. Also production painted parts and/or parts to be stripped for recoating after normal service are typically treated in such type burn-off ovens. The rejected parts can arise from use of hangers or support structures for the parts being treated which have gone through the coating process numerous times placing them in condition where the build up coating can begin to flake off and contaminant the production parts. It becomes necessary to monitor hanger use cycle times in order to ensure that they are thermally processed in a burn-off oven such flaking of the coating can take place.
Typical process hardware and a process method may involve continuous in line hangers or part support structures carrying work pieces through a coating spraying system for coating the work pieces, resulting in the hangers and part support structures likewise being at a minimum partially coated. This requires the hangers to be removed from the production line and to be moved in a cart to the batch type burn-off oven. The burn-off oven heats the contents of the cart to a temperature capable of incinerating the coatings on the hangers or other coated parts, over a period of 3 to 12 hours.
In some cases, some ash or residue remains on the processed parts and it may be removed physically such as by a brushing or washing process. The cleaned hanger or support part can then be placed back in service for the next process cycle. In order for the contaminant or undesirous coating to be incinerated in the burn-off ovens they must attain very high temperatures (depending on the thickness of coating materials). Therefore, extensive time is required for the thermal energy to be transferred from the energy source to the contaminated parts. Typically this energy is transferred using convection heating methods due to the number of parts being treated at one time masking them from the use of radiant, impingment or like type alternate heating methods.
This invention pertains to the art of methods and apparatuses for cleaning contaminants from articles, and more specifically to methods and apparatuses for incinerating the contaminants.
The present invention incorporates the utilization of high watt density electric infrared heaters and other high energy heating methods appropriately designed and arranged to incinerated accumulated coatings on work piece carrier hangers and/or coatings from work pieces for refinishing while they are carried through a burn-off oven which is located in-line with the normal in-line coating process line.
Typically exposure time in the burn-off oven is in the order of one minute. It is not necessary to remove the work piece support carriers or work pieces from the conveyor line to accomplish the desired stripping function in a remote high energy batch heating system.
The electric infrared heaters are specifically designed by utilizing high temperature emitters to create rapid heating rates and incorporate high temperature reflective refractories with critical air cooling provisions for improved heater lamp life and heater longevity. Preferably the high energy heating section is completely enclosed to shield operational personnel and to retain any affluent gases created in the burn-off process.
After the burn-off process the work piece support hangers and/or work pieces to be stripped may pass through a cleaning station for removal of ash residue. The cleaned hardware then continues through the production cycle.
The system is designed for continuous in-line operation and may be utilized during all in-line processing; however, the burn-off oven may be deactivated and programmed for specific utilization time where intermittent usage is adequate. Further, the user may choose to utilize the burn-off oven on a side track in an off-line arrangement from the in-line production arrangement; however, utilizing the advantage of not having to remove the work piece carrier supports.
Where necessary burn-off oven installations incorporate affluent gas removal hardware for transferring such gases to a gas burning incinerator which incinerator is known in the prior art.
The system includes necessary control equipment such as a switch gear, temperature controllers, logistic controllers, safety devices, limiting devices and alarming devices as necessary for system control.
In one aspect the invention is a method of rapid incineration of contaminants on articles in a continuous moving environment without removal of the articles from the conveyance means and includes the following steps. Passing the articles in situ of the conveyance means past a high intensity energy source thereby elevating the temperature of the contaminant on the article to the incineration point. Supplying energy to the high energy source in proportion to the speed of the moving articles whereby the time of the articles within the high energy source equals the time necessary to bring the contaminant to the incineration point.
The invention is also a method of rapid heating continuous moving in-line system articles using a high intensity energy source to enable the articles to be cleaned by rapid incineration of contaminants on the articles without removal of the articles from the in-line system conveyance means thereby saving time required from removal and reinstallation of articles as well as shortening heating time.
The invention also anticipates an apparatus for enclosing a continuous in-line system article high energy incineration station including;
a. a container capable of sustaining a negative pressure;
b. an exhaust system;
c. a low pressure inlet/outlet seal; and
d. an inner face to a gas incinerator burn-off.
The present invention has the advantage over the prior art batch burn-off systems of faster heating to reduce cleaning time in a production environment. More production time is saved because hangers do not have to be removed from the line. The same is true for support structures. Additional time is saved because the hangers and structures do not have to be reinstalled. A further advantage is there is no need to monitor when cleaning is required such as counting the number of coatings on the hangers. Still another advantage is fewer hangers are needed since a batch type oven may be processing hangers while the coating line is in operation. As a result the invention prevents contamination of treated parts by flaking off of contaminant from hangers over due for cleaning, and fewer hangers are needed by the system of the present invention since those in a batch type oven cannot be used in production whereas the same situation does not occur with the in-line system of the present invention.
The present invention enhances efficiency by cleaning hangers every time it is used, if desired, requiring less energy and possibly eliminating the need for physical removal of residue. Further advantages of the present invention will be apparent upon review of the following detailed description.